The relationship between vitamin D and infertility has been extensively researched worldwide over the past 30 years. It has been demonstrated that vitamin D has metabolic/hormonal beneficial effects, especially on polycystic ovary syndrome (PCOS) and endometriosis.
Vitamin D is a secosteroid hormone produced in our skin through the influence of sunlight. It is generally known for its association with bone health. However, its effects beyond bone have started to be better understood in recent times. Vitamin D deficiency is known to be associated with cancer, autoimmune diseases, infectious diseases, cardiovascular diseases, and diabetes. Vitamin D deficiency is defined as having a blood level below 20 ng/ml. Nearly half of the global population is estimated to have a deficiency in vitamin D.
Globally, there are 48.5 million couples facing infertility issues. Vitamin D has multiple effects on the female reproductive system. An association has also been shown between ovarian reserve and vitamin D. Vitamin D deficiency has been linked to endometriosis and polycystic ovary syndrome, which are among the causes of female infertility. Studies suggest that vitamin D supplementation may reduce endometriotic foci. It is known that women diagnosed with obesity and polycystic ovary syndrome have lower levels of vitamin D compared to the general population.
In patients undergoing assisted reproductive technologies with a vitamin D level below 20 ng/ml, the pregnancy rates were found to be lower than in women with vitamin D levels above 30 ng/ml. This is attributed to both lower egg quality and embryo quality in women with vitamin D deficiency. Furthermore, in cases of vitamin D deficiency, the perception of the endometrium is impaired, which affects the implantation of embryos.
In patients with low ovarian reserve, it has been shown that vitamin D supplementation increases anti-Müllerian hormone (AMH) levels. AMH is the most reliable marker for assessing ovarian reserve. In patients with polycystic ovary syndrome, AMH levels are abnormally high. Interestingly, vitamin D supplementation in polycystic ovary syndrome leads to a decrease in AMH levels, indicating positive effects on the ovulation mechanism.
Vitamin D supplementation in patients with vitamin D deficiency has been shown to increase pregnancy and live birth rates while reducing the frequency of miscarriages and various pregnancy complications.
In our practice in Cyprus, we regularly monitor vitamin D levels during IVF treatment. Patients with severe deficiency receive the necessary vitamin D supplementation. For patients with no significant deficiency, we recommend maintenance doses of vitamin D supplementation from the beginning of IVF treatment until the end of pregnancy.
